package com.atguigu.gulimall.product.service.impl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.atguigu.common.utils.PageUtils;
import com.atguigu.common.utils.Query;

import com.atguigu.gulimall.product.dao.CategoryDao;
import com.atguigu.gulimall.product.entity.CategoryEntity;
import com.atguigu.gulimall.product.service.CategoryService;


@Service("categoryService")
public class CategoryServiceImpl extends ServiceImpl<CategoryDao, CategoryEntity> implements CategoryService {

    //等价于baseMapper，因为该实现类继承了ServiceImpl
    @Autowired
    CategoryDao categoryDao;

    @Override
    public PageUtils queryPage(Map<String, Object> params) {
        IPage<CategoryEntity> page = this.page(
                new Query<CategoryEntity>().getPage(params),
                new QueryWrapper<CategoryEntity>()
        );

        return new PageUtils(page);
    }

    @Override
    public List<CategoryEntity> listWithTree() {
        //1.查出所有分类
        List<CategoryEntity> entities = baseMapper.selectList(null);
        //2.组装成父子的树型结构
        //2.1 找到一级的分类
        //使用java8新特性，使用Stream流的过滤器以及Lambda表达式进行编码。
        List<CategoryEntity> level1Menus = entities.stream().
                filter(categoryEntity -> categoryEntity.getParentCid() == 0).
                //给对象的元素添加值
                        map((menu) -> {
                    menu.setChildren(getChildrens(menu, entities));
                    return menu;
                }).
                //对对象中的元素进行排序
                        sorted((menu1, menu2) ->
                        (menu1.getSort() == null ? 0 : menu1.getSort()) - (menu2.getSort() == null ? 0 : menu2.getSort())
                ).
                //获取值
                        collect(Collectors.toList());

        //缺点，只能查询一个树
//        for (CategoryEntity level1Menu : level1Menus) {
//            List<CategoryEntity> childrenList = entities.stream().
//                    filter(categoryEntity -> categoryEntity.getParentCid() == level1Menu.getCatId()).
//                    collect(Collectors.toList());
//            level1Menu.setChildren(childrenList);
//        }


        return level1Menus;
    }

    //批量删除
    @Override
    public void removeMenuByIds(List<Long> asList) {
        //TODO 1、检查当前删除的菜单，是否被别的地方引用
        //逻辑删除,数据库中的show_status字段，0表示被删除，不显示，1表示没被删除，显示
        baseMapper.deleteBatchIds(asList);
    }

    //递归查找所有菜单的子菜单
    private List<CategoryEntity> getChildrens(CategoryEntity root, List<CategoryEntity> all) {
        List<CategoryEntity> collect = all.stream().filter(
                //如果还有子菜单，就需要递归调用
                categoryEntity -> categoryEntity.getParentCid() == root.getCatId()).
                map(categoryEntity -> {
                    //子菜单
                    categoryEntity.setChildren(getChildrens(categoryEntity, all));
                    return categoryEntity;
                }).
                //菜单排序
                        sorted((menu1, menu2) -> (menu1.getSort() == null ? 0 : menu1.getSort()) - (menu2.getSort() == null ? 0 : menu2.getSort())).
                        collect(Collectors.toList());
        return collect;
    }

}